字符设备注册platform平台驱动机制

#include <linux/fs.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/cdev.h>
 #include <linux/ioport.h>
 #include <linux/pci.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <linux/interrupt.h>
 #include <asm/mach/irq.h>
 #include <asm/arch/regs-gpio.h>
 #include <linux/poll.h>
 #include <linux/platform_device.h>/* 参考arch/arm/plat-s3c24xx/devs.c */
/*1. 根据芯片手册来获取资源*/
 staticstruct resource led_resource[] = {
  [0] = {
   .start = 0x56000050,
   .end   = 0x56000057,
   .flags = IORESOURCE_MEM,
  },
  [1] = {
   .start = 5,
   .end   = 5,
   .flags = IORESOURCE_IRQ,
  },
 };void led_release(struct device *dev)
 { }
/*1.构建平台设备结构体，将平台资源加入进来*/
struct platform_device  led_device = {
  .name    = "myled", /* 使用名为"myled"的平台驱动 */
  .id    = -1,
  .dev = {
   .release = led_release,
  },
  .num_resources   = ARRAY_SIZE(led_resource),
  .resource   = led_resource,
 };/*2。把我们的设备资源挂在到虚拟总线的设备连表中去*/
 int led_dev_init(void)
 {
  platform_device_register(&led_device);    
  return 0;
 }void led_dev_exit(void)
 {
  platform_device_unregister(&led_device);
 }module_init(led_dev_init);
 module_exit(led_dev_exit);MODULE_LICENSE("GPL");

#include <linux/fs.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/cdev.h>
 #include <linux/ioport.h>
 #include <linux/pci.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <linux/interrupt.h>
 #include <asm/mach/irq.h>
 #include <asm/arch/regs-gpio.h>
 #include <linux/poll.h>
 #include <linux/platform_device.h>static int major = 0;
static volatile unsigned long *gpio_con;
 static volatile unsigned long *gpio_dat;
 static int pin;
 static struct class *cls;int led_open(struct inode *inode, struct file *file)
 {
  /* 设置对应的引脚为输出引脚 */ *gpio_con &= ~(0x3 << (pin * 2));
  *gpio_con |= (0x1 << (pin * 2));
  
  return 0;
 } ssize_t led_write(struct file *file, const char __user *buf, size_t size, loff_t *offset)
 {
  char ker_buf[1];
  
  /* 根据buf传入的值点/灭灯 */
  /* buf[0] - 亮/灭 , 0 - 亮, 1 - 灭 */ if (size != 1)
  {
   return -EINVAL;
  } copy_from_user(ker_buf, buf, 1);
  
  if ((ker_buf[0] != 0) && (ker_buf[0] != 1))
   return -EINVAL; if (ker_buf[0]) 
  {
   // 某个LED
   *gpio_dat |= (0x1<< pin);
  }
  else
  {
   // 某个LED
   *gpio_dat &= ~(0x1<<pin);
  }
  
  return 1;
 }/*4实现操作硬件的方法*/
 static struct file_operations led_fops = {
  .owner  = THIS_MODULE,
  .open   = led_open,
  .write  = led_write,
 };/*3。实现probe函数*/
 static int led_probe(struct platform_device *dev)
 {
  struct resource *r;
  
  /* 根据平台设备确定点哪一个LED */
  r = platform_get_resource(dev, IORESOURCE_MEM, 0); /*获取到资源以后再进行映射*/
  gpio_con = ioremap(r->start, r->end - r->start + 1);
  gpio_dat = gpio_con + 1; r = platform_get_resource(dev, IORESOURCE_IRQ, 0);
  pin = r->start; /* 注册驱动向内核里面注册我们的字符设备驱动 */
  major = register_chrdev(0, "led", &led_fops); /* sysfs  ==> 挂接到/sys */
  cls = class_create(THIS_MODULE, "led_class");
  class_device_create(cls, NULL, MKDEV(major, 0), NULL, "led"); // mdev会根据/sys下的这些内容创建/dev/led
 return 0;
 }int led_remove(struct platform_device *dev)
 {
  unregister_chrdev(major, "led");
  class_device_destroy(cls, MKDEV(major, 0));
  class_destroy(cls);
  iounmap(gpio_con);  
  return 0;
 }/*1。构建平台驱动结构体，不知道的时候可以看别人的*/
 static struct platform_driver led_driver = {
  .probe  = led_probe,     /* 平台总线下增加一个平台设备时，调用枚举函数 */ 
  .remove  = led_remove,    /* 平台总线下去掉一个平台设备时，调用remove函数 */ 
  .driver  = {
   .name = "myled",       /* 能支持名为"myled"的平台设备 */
   .owner = THIS_MODULE,
  },
 };/*2。注册，把我们的驱动加入到平台设备驱动连表中去*/
 static int led_drv_init(void)
 {
  platform_driver_register(&led_driver);
  return 0;
 }static int led_drv_exit(void)
 {
  platform_driver_unregister(&led_driver);
  return 0;
 }module_init(led_drv_init);
 module_exit(led_drv_exit);MODULE_LICENSE("GPL");